Acyclovir is a new HBV-DNA polymerase inhibitor, having broad spectrum antiviral activity against animal and human viruses.
Kristl (Int. J. Phar. 1996, 139, 231-235) reported some crystal forms of acyclovir, including 2/3 hydrate, instable anhydrous form and anhydrous (stable) form 1 and anhydrous form 2. The results showed that, compared with other forms, 2/3 hydrate had higher water solubility and thus higher bioavailability, and was suitable for preparing antiviral preparations. The acyclovir in European Pharmacopeia is 2/3 hydrate. However, the preparation process and XRD data of acyclovir 2/3 hydrate have not been reported yet. Young (Arch. Pharm. Res. 2008, 31, 231-234) disclosed an acyclovir hydrate (Form 3), which had a weight-loss as measured by Thermogravimetric Analysis (TGA) of about 6.74%.